The present invention relates to a disk controller. In particular, it relates to a redundant array of inexpensive disks (RAID) controller.
Dynamic random access memory (DRAM) nowadays has become a common memory element in a digital data processing device. As usual, the DRAM is electrically contacted in the slots on a circuit board in the form of memory module hardware implementation. Please refer to FIG. 1(a) and FIG. 1(b). FIG. 1(a) is the exterior view of a 168-pin memory module (dual inline memory module, DIMM), which is mostly employed in a desktop computer. FIG. 1(b) is the exterior view of a 144-pin memory module (small outline dual inline memory module, SODIMM), which is typically employed in a laptop computer. For the purpose of rendering 144-pin SODIMM feasible in a laptop computer, the length of a SODIMM (67.6 mm) is far smaller than that of a 168-pin DIMM (133.35 mm), and therefore the pin number of the SODIMM is less than that of the DIMM by 24 (168xe2x88x92144=24).
In order to ensure the accuracy while the memory module is transmitting data, miscellaneous error-prevention means are developed. In particular, error correction code (ECC) and parity check are the most common error-prevention means. Owing to the limitation of the functions that the memory module can support, currently the error-prevention function for correcting the memory module errors, e.g. ECC or parity check, is supported on a 168-pin DIMM only. With respect to the 144-pin SODIMM, the error-prevention function is still unsupported thus far.
Please refer to FIG. 2 which shows a conventional redundant arrays of inexpensive disks (RAID) controller board with a 168-pin DIMM slot mounted thereon. The memory module slot 21 is used to insert therein a 168-pin DIMM 22 (the DIMM 22 has multiple synchronous dynamic random access memory 221, . . . , 22n), and the I/O processor 23 transmits a data clock signal through multiple connection lines 24 connecting between the I/O processor 23 and the memory module slot 21. Each one of the connection 24 lines has the same length of X (where X should be kept as small as possible). The feedback data clock line 25 has a length of X+a (where a varies with the category and type of the I/O processor 23, e.g. if the I/O processor is an Intel i960RN processor, a will be 4 inches) and be connected with a microcapacitor in parallel for tuning the timing clock.
The dimension of aforesaid RAID controller board is usually confined to that of the chassis of a standard 5.25 inches hard disk or that of a bus interface card for a standard personal computer, and therefore the 168-pin DIMM slot with the length of 133.35 mm will make the circuit board very crowded, which causes the disturbance and limitation on the circuit layout. As a result, the dimension of the circuit board can not be reduced further. Consequently, selecting the 144-pin SODIMM shown in FIG. 1(b) as the memory module on a RAID controller board is a better choice because the length of the memory module slot can be greatly reduced below 7 cm and the dimension of the circuit board can be reduced further. Unfortunately, the SODIMM does not support the error correction function, and it will severely affect the performance of a RAID controller which requires a powerful error detection and compatibility function.
There arose a need for the applicant to develop a disk controller to dispose of the shortcomings encountered in the prior art.
An object of the present invention is to provide a disk controller, which not only has a reduced dimension but can support the error-prevention function.
According to the present invention, the disk controller of the present invention includes: a circuit board, a memory module slot mounted on the circuit board for inserting therein a memory module, an I/O processor mounted on the circuit board and electrically connected with the memory module slot for transmitting a data clock signal and an error-prevention data, and a random access memory integrated chip (RAM IC) mounted on the circuit board and electrically connected with the I/O processor for storing the error-prevention data.
Preferably, the disk controller is a redundant arrays of inexpensive disks (RAID) controller, and the memory module is a 144-pin small outline dual inline memory module (SODIMM).
Preferably, the circuit board has a dimension smaller than or equal to the dimension of chassis of a standard hard disk drive.
Preferably, the random access memory integrated chip is a synchronous dynamic random access memory integrated chip (SDRAM IC).
Alternatively, the error-prevention data is an error correction code (ECC) or a parity check.
Preferably, the length of the connection line connecting between the I/O processor and the RAM IC is longer than that of the connection line connecting between the I/O processor and the memory module slot by an additional length.
In accordance with the present invention, the I/O processor is an Intel i960RN processor, and the aforementioned additional length will be 3.4 inches.
In accordance with the present invention, the disk controller further includes a feedback data clock line electrically connected with the I/O processor in parallel for performing feedback to the I/O processor in order to tune the timing clock of the data clock signal.
In accordance with the present invention, the feedback data clock line and the connection line connecting between the I/O processor and the RAM IC are respectively connected with microcapacitors in parallel.
According to another aspect of the present invention, the redundant arrays of inexpensive disks (RAID) controller includes: a redundant arrays of inexpensive disks (RAID) controller board, a memory module slot mounted on said controller board for inserting therein a 144-pin small outline dual inline memory module (SODIMM), an I/O processor mounted on said controller board and electrically connected with said memory module slot for transmitting a data clock signal and an error-prevention data, and a random access memory integrated chip (RAM IC) mounted on said controller board and electrically connected with said I/O processor for storing said error-prevention data, wherein the length of the connection line connecting between said I/O processor and said RAM IC is longer than that of the connection line connecting between said I/O processor and said memory module slot by an additional length.
Now the foregoing and other features and advantages of the present invention will be more clearly understood through the following descriptions with reference to the accompanying drawings, in which: